This disclosure relates to a cooling strategy for use in a generator.
Electrical generators typically include a shaft that is driven for rotation and which carries a plurality of field coils and/or permanent magnets. The generator may be used to also drive a hydraulic pump, such as for cooling the generator or other components of a system. The pump may communicate cooling oil back to the generator to maintain the generator at a desired operating temperature.
Different cooling schemes for distributing the cooling oil may be used for different types of generators. For instance, generators having greater than four poles have a significant amount of end winding area onto which the cooling oil can be sprayed to remove heat from the generator (i.e., impingement cooling scheme).
In generators having four poles or less, there is less coil end winding area and impingement cooling is therefore ineffective. In this case, a flood cooling scheme may be used in which the coils are contained within an outer housing and cooling oil is provided into one end of the housing to flow outwardly and then around the coils. However, flood cooling requires a robust housing structure to contain relatively high pressures created from the centrifugal force of the cooling oil flow within the housing. Moreover, for generators having short coil lengths and large diameters, the pressure would be greater and require large, expensive containment structures.